Incomplete OID Retrieval: SNMP Walk (nextCmd/bulkCmd) Fails to Capture All OIDs about pysnmp HOT 6 CLOSED

There were quite a few reports on walk operations, so you need to enable debugging https://www.pysnmp.com/pysnmp/examples/#using-these-examples and then compare to those.

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Hi @lextm,

Thank you for your prompt response. I have utilized the debug command as suggested and have collected the following results from my snmp walk:

When the returned value is null (observed in the standard SNMP walk results) no errors are raised. The error-status is 'noError'. But it stops everytime a null value is introduced in the walk. I conducted the walk from various angles, consistently obtaining the same results. In the alternative SNMP utility, there are over 300 null values from 4700 values, all reacting the same when I change the walk root subtree.

I am eager to contribute to resolving this issue, given that SNMP walking is a critical component of my application. I am willing to assist with development or provide any information needed for debugging. If you prefer, I am open to allowing you to log onto my machine for direct debugging.

Here is a snippet of the response for the OID with a null value:

2023-11-20 09:53:51,897 pysnmp: sendPdu: current time 5 ticks, one tick is 0.5 seconds
2023-11-20 09:53:51,897 pysnmp: sendPdu: new sendPduHandle 727660, timeout 40.0 ticks, cbFun <bound method CommandGenerator.processResponsePdu of <pysnmp.entity.rfc3413.cmdgen.BulkCommandGenerator object at 0x000002B3F98A7DC0>>
2023-11-20 09:53:51,911 pysnmp: sendPdu: MP succeeded
2023-11-20 09:53:51,915 pysnmp: receiveMessage: msgVersion 0, msg decoded
2023-11-20 09:53:51,917 pysnmp: receiveMessage: MP succeded
2023-11-20 09:53:51,917 pysnmp: receiveMessage: PDU GetResponsePDU:
request-id=2315122
error-status=noError
error-index=0
variable-bindings=VarBindList:
VarBind:
name=1.3.6.1.2.1.43.8.2.1.16.1.1
value=ObjectSyntax:
simple=SimpleSyntax:
empty=

2023-11-20 09:53:51,928 pysnmp: sendPdu: current time 5 ticks, one tick is 0.5 seconds
2023-11-20 09:53:51,936 pysnmp: sendPdu: new sendPduHandle 727661, timeout 40.0 ticks, cbFun <bound method CommandGenerator.processResponsePdu of <pysnmp.entity.rfc3413.cmdgen.BulkCommandGenerator object at 0x000002B3F98A7DC0>>
2023-11-20 09:53:51,938 pysnmp: sendPdu: MP succeeded
2023-11-20 09:53:51,940 pysnmp: receiveMessage: msgVersion 0, msg decoded
2023-11-20 09:53:51,942 pysnmp: receiveMessage: MP succeded
2023-11-20 09:53:51,943 pysnmp: receiveMessage: PDU GetResponsePDU:
request-id=2315124
error-status=noError
error-index=0
variable-bindings=VarBindList:
VarBind:
name=1.3.6.1.2.1.43.8.2.1.16.1.1
value=ObjectSyntax:
simple=SimpleSyntax:
empty=

Here is a response from a oid that returns Samsung External Media Handler:

2023-11-20 09:53:51,830 pysnmp: sendPdu: current time 4 ticks, one tick is 0.5 seconds
2023-11-20 09:53:51,843 pysnmp: sendPdu: new sendPduHandle 727659, timeout 40.0 ticks, cbFun <bound method CommandGenerator.processResponsePdu of <pysnmp.entity.rfc3413.cmdgen.BulkCommandGenerator object at 0x000002B3F98A7DC0>>
2023-11-20 09:53:51,879 pysnmp: sendPdu: MP succeeded
2023-11-20 09:53:51,892 pysnmp: receiveMessage: msgVersion 0, msg decoded
2023-11-20 09:53:51,894 pysnmp: receiveMessage: MP succeded
2023-11-20 09:53:51,895 pysnmp: receiveMessage: PDU GetResponsePDU:
request-id=2315120
error-status=noError
error-index=0
variable-bindings=VarBindList:
VarBind:
name=1.3.6.1.2.1.43.8.2.1.15.1.2
value=ObjectSyntax:
simple=SimpleSyntax:
string=Samsung External Media Handler

2023-11-20 09:53:51,897 pysnmp: receiveMessage: cache read by sendPduHandle 727659
2023-11-20 09:53:51,897 pysnmp: receiveMessage: processResponsePdu succeeded
2023-11-20 09:53:51,897 pysnmp: sendPdu: securityName s-5824012256909706693, PDU
GetNextRequestPDU:
request-id=2315122
error-status=noError
error-index=0
variable-bindings=VarBindList:
VarBind:
name=1.3.6.1.2.1.43.8.2.1.15.1.2
value=ObjectSyntax:
simple=SimpleSyntax:
empty=

I appreciate your assistance and look forward to your guidance on resolving this matter.

Best regards,
Christo

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I managed to find a better solution for walking.

https://github.com/lextudio/pysnmp

@lextm thanks for forking the above and improving it :)

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https://github.com/lextudio/pysnmp

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Then the changes might come from pysnmp community patches (from Splunk or others) that have been integrated into 5.0 releases.

You can read #429 to learn more about the ecosystem changes.

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Again appreciate the initiative @lextm!

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